Question

Examine the amino acid sequence from three organisms (A, B, and C). Which two organisms are the most closely related? Organism A: Val-Ser-Thr-Val Organism B: Leu-Ala-Leu-Ala Organism C: Val-Ser-Asp-Met

Answer 1

To determine which two organisms are most closely related based on their amino acid sequences, we can compare the sequences of the three organisms.

- **Organism A**: Val-Ser-Thr-Val
- **Organism B**: Leu-Ala-Leu-Ala
- **Organism C**: Val-Ser-Asp-Met

**Comparison**:

1. **Organism A vs. Organism B**:
- Sequence: Val-Ser-Thr-Val vs. Leu-Ala-Leu-Ala
- There are no amino acids in common between these two sequences.

2. **Organism A vs. Organism C**:
- Sequence: Val-Ser-Thr-Val vs. Val-Ser-Asp-Met
- They share two amino acids in common: **Val** and **Ser** (the first two residues).

3. **Organism B vs. Organism C**:
- Sequence: Leu-Ala-Leu-Ala vs. Val-Ser-Asp-Met
- There are no amino acids in common between these two sequences.

**Conclusion**:
Organism A and Organism C share two amino acids in their sequences (Val and Ser), suggesting that they are more closely related to each other compared to Organism B, which has no similarities with either A or C. Therefore, **Organism A and Organism C are the most closely related**.